1. Field of the Invention
The present invention generally relates to liquid containers, methods of assembling and disassembling liquid containers, and image forming apparatuses.
2. Description of the Related Art
There are various types of image forming apparatuses, such as printers, facsimile machines, copy machines, plotters, and multifunction peripherals incorporating multiple image forming functions. For example, an inkjet recording apparatus is a fluid-discharging type printer that discharges droplets of ink using a recording head. The discharged droplets of ink attach onto a recording medium, such as a sheet of paper, an OHP sheet, or any other material onto which ink droplets or other fluid can attach in order to form, print, record, or transfer an image on the recording medium. The image forming apparatus of the fluid-discharging type includes a serial type and a line type. In the serial type, the recording head is moved in a main-scan direction as it discharges ink droplets. In the line type, the recording head discharges ink droplets without moving.
The recording medium on which an image is formed by the image forming apparatus of the fluid-discharge type may include various materials, such as paper, threads, fibers, cloth, leather, metal, plastics, glass, wood, and ceramics. The “image” printed, formed, or recorded on, or transferred onto, for example, the recording medium may include not only meaningful characters or figures but also random or apparently meaningless shapes or patterns. The “ink” may include a recording fluid, a fixing-treatment fluid, a DNA sample, a resist fluid, or any other fluid capable of forming an image on the recording medium. The “image” refers not only to two-dimensional images but also three-dimensional images, such as an image printed on a three-dimensional object.
Typically, an inkjet recording apparatus (image forming apparatus) includes a sub-tank (which may be referred to as a “buffer tank” or “a head tank”) and an ink cartridge (which may be referred to as a “main tank”). The sub-tank is mounted on a carriage that carries a recording head, and ink is supplied from the sub-tank to the recording head. The main tank is detachably attached to a hollow body of the image forming apparatus (which may be hereafter referred to as an “apparatus main body”). The sub-tank is supplied with ink from the main tank, and the ink is then supplied from the sub-tank to the recording head.
The ink cartridge (main tank) may have a double-bag structure within a cartridge case in which an outer air bag is disposed outside an inner ink bag into which outer bag compressed air is introduced. By supplying the compressed air into the outer air bag, the inner ink bag is pressurized, thus causing the ink to be supplied from the ink bag to the sub-tank. In such a pressurized ink cartridge, the cartridge case is subject to a high pressure. There is also an increasing trend to increase the pressure applied to the cartridge so as to increase the volume of ink supplied per unit time for achieving higher printing speed, or to enable the supply of high-viscosity ink having a quick-drying property.
Patent Document 1 discloses an ink cartridge that includes a thin, substantially rectangular-solid shaped cartridge case in which an ink pack is housed. The cartridge case includes a hollow body and a lid portion. Patent Document 2 discloses that ink is contained in a bottle-shaped case formed by blow molding.    Patent Document 1: JP2006-82290A    Patent Document 2: JP2002-505212A
As mentioned above, there is a need to increase the supply of ink in a stable manner for increasing the speed of image formation. The ink cartridge according to Patent Document 1 includes a hollow body and a lid portion that are divided along a plane parallel to two of the six faces of the rectangular solid shape that have the largest areas. As a result, when a large load is applied to the cartridge case, the hollow body and the lid portion may break apart along the dividing plane.
On the other hand, there is also the demand to fill the ink bag with “deaerated ink” from which air is removed as much as possible in order to prevent air from entering a fluid supply channel of an image forming apparatus. In one method to fill the ink bag while preventing the entry of air into ink, air may be initially suctioned from an ink bag via its inlet, with the ink bag retained in place with a pair of flat plates and the like in a smoothly folded state, and then ink is injected into the ink bag which is in a reduced-pressure condition, followed by hermetically sealing the inlet. In another method, after the ink bag is filled with ink via its inlet, the ink bag is disposed such that the inlet is facing downward, so that air collects at the top opposite to the inlet. The ink bag is then hermetically sealed such that the upper portion of the ink bag where the air is mixed with ink is isolated. In any of these methods, the ink bag needs to be filled with ink before the ink bag is housed in the cartridge case.
However, in the case of the bottle-shaped case discussed in Patent Document 2, the inlet of the case is reduced in size so as to increase the pressure resistance of the cartridge case. Thus, an ink bag filled with ink cannot be housed in the case during assembly; namely, the ink cannot be deaerated by any of the aforementioned methods.